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The principle of equivalence and projective structure in space-times

G. S. Hall·D. P. Lonie
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Abstract

This paper discusses the extent to which one can determine the space-time metric from a knowledge of a certain subset of the (unparametrised) geodesics of its Levi-Civita connection, that is, from the experimental evidence of the equivalence principle. It is shown that, if the space-time concerned is known to be vacuum, then the Levi-Civita connection is uniquely determined and its associated metric is uniquely determined up to a choice of units of measurement, by the specification of these geodesics. It is further demonstrated that if two space-times share the same unparametrised geodesics and only one is assumed vacuum then their Levi-Civita connections are again equal (and so the other metric is also a vacuum metric) and the first result above is recovered.

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G. S. Hall, D. P. Lonie. 2007-03-21. The principle of equivalence and projective structure in space-times. https://doi.org/10.1088/0264-9381%2F24%2F14%2F005

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